Phylogenetic position of Cyperus clandestinus (Cypereae, Cyperaceae) clarified by morphological and molecular evidence

Abstract

Extreme morphological reduction and convergent evolution can obscure taxonomic relationships. This phenomenon is frequently encountered in Cyperaceae, where characters traditionally used to diagnose genera have been shown to have evolved independently multiple times. The Ethiopian high‐altitude perennial first described as Cyperus clandestinus was subsequently moved to Ficinia because it has spiral glume arrangement, unlike typical Cyperus species, which have distichous glume arrangement. However, this position has remained uncertain as no nutlets have previously been studied to establish the presence or absence of the gynophore – the synapomorphy for Ficinia. We resolve this 140‐year‐old puzzle by describing the morphology of the nutlet, which lacks a gynophore, and use DNA sequence data to resolve the taxon within Cyperus. Cyperus clandestinus was found to be closely related to Remirea maritima and Cyperus cyperoides in the C4Cyperus clade, whose members predominantly have distichously arranged glumes. This provides further evidence for the unreliability of glume arrangement as a character to distinguish between members of the Cyperus and Ficinia clades, whereas gynophore presence is more congruent with molecular data.

Towards a new classification of the giant paraphyletic genusCyperus(Cyperaceae): phylogenetic relationships and generic delimitation in C4Cyperus

“…The first subclade, also retrieved in previous studies (e.g. Muasya et al ., , in press; Larridon et al ., ), is represented by Cyperus cuspidatus Kunth (and its Malagasy relative C. waterlotii Cherm . ).…”

“…Brongn. (two species) appears to be at the base of the Cyperus clade (Muasya et al ., , in press), but this needs further confirmation. Although molecular phylogenetic studies have revealed that all of these genera are nested in Cyperus (e.g.…”

“…with the C 4 photosynthetic pathway as a synapomorphy (e.g. Muasya, Simpson & Chase, ; Muasya et al ., , , in press; Besnard et al ., ; Larridon et al ., ). The nine C 4 segregate genera represent c. 30% of diversity in the C 4 Cyperus clade.…”

“…However, neither the distichy of the glumes nor the absence of a perianth can be regarded as phylogenetically informative characters (e.g. Vrijdaghs et al ., ; Muasya et al ., , b, in press). Currently, members of Cypereae are circumscribed by the presence of a Cyperus ‐type embryo or the similar Ficinia ‐type embryo (Van der Veken, ; Goetghebeur, ; Muasya et al ., , b).…”

Taxonomy and phylogenetic position of Fimbristylis fusiformis, a new species of Cyperaceae from Thailand

“…Using a silica gel dried sample of the new taxon, DNA was extracted using the CTAB method and the ITS marker amplified and sequenced using standard protocols and primers (Muasya et al 2014). Contigs of forward and reverse sequences were assembled using the STADEN package (Staden 1996).…”